The background arrangement of components includes a conducting housing which has in one wall a common port CP and a pedestal port PP for respective connection to coaxial distribution cable, sometimes known as `hard line` and in the opposed wall of the housing has an aerial port AP for similar connection. The invention however also applies to `dedicated` two-port housings having only a common port and either an aerial or a pedestal port. A plate of insulating material, of the type commonly called a `motherboard`, carries RF and alternating current (`AC`) circuitry and supports and is connected to the RF circuitry (commonly a coupler and splitter), for connection to customer ports, also known as `secondary` or tap ports. There is an RF through path on the motherboard which is connectable at one end to the pin of the coaxial cable which is at the common port. The other end of the RF path on the motherboard is connectable to either the centre pin of a coaxial gable connected to the aerial port or the centre pin of a coaxial conductor connected to the pedestal port. An AC path (since the coaxial cable typically carries RF and AC) typically diverges from the RF to pass through an inductor adjacent one end of such path and joins it again, near the other end of the RF path. The RF path (unless bypassed) connects to active or passive RF circuitry. Typical of the passive circuitry is a coupler and splitter for providing RF signals to the tap ports. The coupler is designed to operate on RF signals in only one direction in the path. Hence when, as is later discussed, the RF path through the housing is reversed, means must be provided for reversing the coupler relative to the remainder of the RF through line. The housing is usually one of a number connected in series with others at spaced intervals along lengths of coaxial cable forming part of the distribution network. It is undesireable if an RF through path is interrupted in one housing since it interrupts the reception of customers downstream in the distribution network. Bypass means are therefore provided if the coupler is removed.